The Troggs' ' Wild Thing', which uses I, IV and V chords). Many simple traditional music, folk music and rock and roll songs use only these three chord types (e.g. These three triads include, and therefore can harmonize, every note of that scale. The triads are referred to as the tonic chord (in Roman numeral analysis, symbolized by 'I'), the subdominant chord (IV), and the dominant chord, (V), respectively. The diatonic harmonization of any major scale results in three major triads, which are based on the first, fourth, and fifth scale degrees. The harmonic function of any particular chord depends on the context of the particular chord progression in which it is found. A chord built upon the note E is an E chord of some type (major, minor, diminished, etc.) Chords in a progression may also have more than three notes, such as in the case of a seventh chord (V 7 is particularly common ) or an extended chord. Therefore, a seven-note diatonic scale allows seven basic diatonic triads, each degree of the scale becoming the root of its own chord. Thus the chord progression E minor–F–G can be described as three–four–five, (or iii–IV–V).Ī chord may be built upon any note of a musical scale. Chords built on several scale degrees are numbered likewise. The key note, or tonic, of a piece of music is called note number one, the first step of (here), the ascending scale iii–IV–V. On the other hand, bebop jazz songs may have 32-bar song forms with one or two chord changes every bar. Some punk and hardcore punk songs use only a few chords. Some jazz-funk songs are based on a two-, three-, or four-chord vamp. Funk emphasizes the groove and rhythm as the key element, so entire funk songs may be based on one chord.

Some pop and rock songs from the 1980s to the 2010s have fairly simple chord progressions. The complexity of a chord progression varies from genre to genre and over different historical periods. For example, if the bandleader asked the band to play this chord progression in the key of C major, the chords would be C–C–C–C, F–F–C–C, G–F–C–C if the bandleader wanted the song in G major, the chords would be G–G–G–G, C–C–G–G, D–C–G–G and so on. By thinking of this blues progression in Roman numerals, a backup band or rhythm section could be instructed by a bandleader to play the chord progression in any key. Thus, a simple version of the 12-bar blues might be expressed as I–I–I–I, IV–IV–I–I, V–IV–I–I. For example, rock and blues musicians often think of the 12-bar blues as consisting of I, IV, and V chords. In rock and blues, musicians also often refer to chord progressions using Roman numerals, as this facilitates transposing a song to a new key. In the first chord, C major, the 'C' indicates that the chord is built on the root note 'C' and the word 'major' indicates that a major chord is built on this 'C' note. For example, the previously mentioned chord progression, in the key of C major, would be written as C major–A minor–D minor–G major in a fake book or lead sheet. In many styles of popular and traditional music, chord progressions are expressed using the name and ' quality' of the chords. Chord progressions, such as the common chord progression I–vi–ii–V, are usually expressed by Roman numerals in Classical music theory. In tonal music, chord progressions have the function of either establishing or otherwise contradicting a tonality, the technical name for what is commonly understood as the ' key' of a song or piece. In these genres, chord progressions are the defining feature on which melody and rhythm are built. Chord progressions are the foundation of popular music styles (e.g., pop music, rock music), traditional music, as well as genres such as blues and jazz. Chord progressions are the foundation of harmony in Western musical tradition from the common practice era of Classical music to the 21st century.

In a musical composition, a chord progression or harmonic progression (informally chord changes, used as a plural) is a succession of chords. The chords shown are F major, G major, and C major. A IV–V–I progression in the key of C major.

Coming back to life chords